没看懂这道题到底想怎么反转，反正过了

public String ReverseSentence(String str) {
            if (str==null||str.trim().length()==0)
            return str;
        String res="";
        int i=0;
        for (;i<str.length();i++){
            char c = str.charAt(i);
            if (!(c>='a' && c<='z' || c>='A' && c<='Z')){
                break;
            }
        }
        if(i<str.length()){
            String s1 = str.substring(0, i);
            String s2 = str.substring(i+1);
            String[] split = s2.split(" ");
            for (int j=split.length-1;j>=0;j--){
                res=res+split[j]+" ";
            }
            return (res+s1+str.charAt(i)).trim();
        }else 
            return str; 
    }